If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

The opposite of what? The OALDCE link you give says (accurately) that in Br Eng there are two forms. It also suggests that the one with schwa is the more common.

In fact, when 'that' is used as a demonstrative adjective ('I want that one') or pronoun 'That's what I want') it's always strong (pronounced /æ/). In the nature of demonstratives, it couldn't not be strong.

When 'that' is used as subordinating conjunction, it's usually weak (/ǝ/) - but not always:

For example (of the exception), in the song Show me:

'Anyone who's ever been in love will tell you that (/æ/)
This is no time for a chat.'

I expect OALDCE makes this distinction somewhere, but I don't have time to look.